We would be in trouble, that's certain, but fortunately, solar and electric powered vehicals are already in existance, so the crisis would simply be a matter of producing enough of these vehicals to replace people's obsolete gas vehicals. That seems like an immense obstacle, but consider that the supply of petroleum won't vanish overnight, and the world will have years to prepare for the inevitable. Those years will be enough time to get the gas dependant parts of the world outfitted with the already viable, but simply unpopular alternate power.
